Thin glass sheets have found use in many optical, electrical or optoeletrical devices, such as liquid crystal (LCD) displays, organic light-emitting diode (OLED) displays, solar cells, as semiconductor device substrates, color filter substrates, cover sheets, and the like. The thin glass sheets, having a thickness of from several micrometers to several millimeters, may be fabricated by a number of methods, such as float process, fusion down-draw process (a method pioneered by Corning Incorporated, Corning, N.Y., U.S.A.), slot down-draw process, and the like. It is highly desired that these glass substrates have high strength, so that they can withstand the mechanical impact that they may encounter during finishing, packaging, transportation, handling, and the like. The atomic network of glass materials is intrinsically strong. However, defect in the surface of a glass sheet, including the major surface and edge surface, can propagate quickly into the network when subject to stress over a certain threshold. Because these substrates normally have relatively high main surface quality with low number of scratches and the like, their strength are largely determined by the edge quality. An edge with small amounts of defects is highly desired for high edge strength of a glass material.
The production of a glass sheet frequently includes a step of cutting by mechanical score-and-break, laser score-and-break or direct laser full-body cutting. Those processes invariably result in a glass sheet having two major surfaces connected by an edge surface substantially perpendicular to the major surfaces. Thus, at the intersection regions between the major surfaces and the edge surface, one may observe sharp, 90° corners. When under a microscope, one can observe a large number of defects such as cracks in the corners, especially where mechanical scoring is used. These corners, when impacted during packaging, handling and use, can easily break, leading to chipping, crack propagation and even sheet rupture, none of which is desirable.
Traditionally, the pre-finishing edges of a glass sheet has been ground and optionally polished. However, the existing finishing methods suffered from one of the more of the following drawbacks: (i) insufficient resultant edge quality; (ii) low throughput; and (iii) low consistency of finished edge quality. Besides, as the glass sheets used for the displays are becoming thinner and thinner, existing finishing methods acceptable for glass sheets with large thickness were found inadequate.
Thus, there is a genuine need of an improved glass sheet edge finishing method. The present invention meets this and other needs.